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I was recent­ly doing some his­tor­i­cal research on my house when I came across a 1910 “jury list” for my neigh­bor­hood. For some rea­son it also lists the res­i­dents’ occu­pa­tions. Some good ones:

As one of my more ridicu­lous spare-time endeav­ours, I am tin­ker­ing around
with his­toric (1870, 1893, and 1908) maps of Dana, Mass­a­chu­setts. I’m
try­ing to over­lay scans of the maps onto a mod­ern coor­di­nate sys­tem so, for
exam­ple, they could be viewed in Google Earth. Under ordi­nary cir­cum­stances,
I could sim­ply match up fea­tures like roads and rivers, which don’t change
much over time. But in this case I want to rely heav­i­ly on lat­i­tude and
lon­gi­tude because much of the land around Dana is gone.

Most of you who have picked up a USGS topo­graph­i­cal map are prob­a­bly
famil­iar with NAD83 coor­di­nates. They are sim­i­lar to the WGS84
coor­di­nates used by GPS systems—but WGS84 coor­di­nates are always on the move
due to mea­sure­ment error and (believe it or not) plate tec­ton­ics. The NAD83
cood­i­nate sys­tem is linked to the North Amer­i­can plate and defined with
ref­er­ence to met­al surveyor’s bench­marks plant­ed in the ground all over the con­ti­nent.

Between 1927 and 1983, the stan­dard datum was NAD27. Now I knew that NAD27
was based on a sim­ple ellip­ti­cal mod­el of the Earth, and that the entire
con­ti­nent had to be sur­veyed by hand in order to fig­ure it out. But until
tonight I did not know that for 56 years the geo­det­ic cen­ter of the Earth
was defined as… Meades Ranch, Kansas.
(Appar­ent­ly the ranch is a nerd-tourism spot. With per­mis­sion from the own­ers you can take pic­tures of the bench­marks set into two rocks at the cen­ter of the world.)

Back to my ques­tion: what was the datum in use pri­or to 1927 when my
maps were drawn? I still haven’t found the answer to my ques­tion.
Per­haps the accu­ra­cy of sur­vey­ing at the time makes it a moot point. I’ll
prob­a­bly have cor­re­late my maps by brute force.

Now about the land. If you haven’t been to Dana, Mass­a­chu­setts before,
I’m hard­ly sur­prised. It doesn’t exist. The town was dis­in­cor­po­rat­ed,
dis­man­tled, and shipped away in 1938 when the Swift Riv­er was dammed to
cre­ate the Quab­bin Reser­voir. Today the area is closed to traf­fic and
filled with about 412 bil­lion gal­lons of water (155 mil­lion gal­lons
of which flow into Boston’s faucets every day). That’s not to say you
can’t vis­it Dana today—but that will have to be the sub­ject of a future post.